The Addition Property of Equality states that adding the same number to each side of an equation yields an equivalent equation.

The Subtraction Property of Equality is similar to the Addition one, with the exception being the sign used — subtracting the same number from each side of an equation yields an equivalent equation.

Either of these properties can be used when eliminating a term in an equation. Deciding which to use depends on if the term is being added to or subtracted from the variable.